Hello? Hell... o?

Hello? Hell..o? is a Japanese RPG horror game. All of the events trigger different events.
A young man named Kazuki is living alone in his apartment. Every time he looks around his apartment, he finds something that reminds him of Akari, his deceased girlfriend. Recently, his old phone starts ringing and he hears a familiar voice on the other line. What can he do to stop this and will it end well for him and Akari?